Variable Compression Piston Rod Damper
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Solution Overview
Problem
In variable compression devices, the piston rod can collide with the regulation member due to inertial forces when combustion pressure is not applied, leading to potential large forces being applied to the regulation member, which can cause damage.
Innovation Solution
A variable compression device is designed with a second fluid chamber acting as a damper between the piston rod and the regulation member, along with a flow rate regulation unit and an absorption member to absorb collision energy, preventing large force collisions and reducing impact on the regulation member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a regulation member is provided to regulate movement of the piston rod, then the compression ratio can be controlled, but the piston rod may collide with the regulation member when inertial force exceeds combustion pressure
Solution Approach 1:
A second fluid chamber is provided between the piston rod and the regulation member to store working fluid that acts as a cushion. When the piston rod moves upward due to inertial force, the working fluid in the second fluid chamber compresses to absorb the impact energy, preventing direct collision between the piston rod and the regulation member. This beforehand cushioning mechanism resolves the contradiction by maintaining reliability while preserving compression ratio control functionality.
Solution Approach 2:
The second fluid chamber filled with working fluid serves as an intermediary element between the piston rod and the regulation member. Instead of allowing direct contact, the compressible working fluid mediates the interaction, absorbing inertial forces during upward motion and transmitting controlled forces during downward motion. This intermediary mechanism enables both reliable collision prevention and effective compression ratio regulation.
2Adaptability or versatility
If the piston rod moves freely to regulate compression ratio, then operational flexibility is improved, but large collision forces may be applied to the regulation member
Solution Approach 1:
The second fluid chamber pre-filled with working fluid provides beforehand cushioning against upward inertial forces. When the piston rod accelerates upward, the working fluid compresses to absorb the impact, reducing the force transmitted to the regulation member. This allows the piston rod to move freely for compression ratio adjustment while protecting against excessive collision forces.
Solution Approach 2:
The inertial force that causes harmful collision is converted into a beneficial compression of the working fluid in the second fluid chamber. The kinetic energy of the upward-moving piston rod is transformed into potential energy of the compressed working fluid, which then dissipates the energy through controlled release or heat. This converts the harmful collision force into a beneficial damping effect that protects the regulation member while maintaining operational flexibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents piston rod collisions with the regulation member by maintaining hydraulic oil in the second fluid chamber as a damper and absorbs collision energy through elastic deformation, reducing the impact on the regulation member.
Implementation Method 1
a second fluid chamber which is provided between the piston rod and the regulation member and is configured to store the working fluid so as to operate as a damper
Implementation Method 2
a first fluid chamber which is configured to move the piston rod in a direction in which a compression ratio is increased by supplying a pressurized working fluid thereto
Implementation Method 3
an absorption member which is fixed to the regulation member or the piston rod, and is configured to absorb collision energy between the regulation member and the piston rod by elastic deformation
Data Source
Figure 1
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Figure 3
AI summary
A variable compression device of the disclosure includes a piston rod (6), a first fluid chamber (R3) which is configured to move the piston rod in a direction in which a compression ratio is increased by supplying a pressurized working fluid thereto, a regulation member (7c) which is configured to regulate movement of the piston rod in a direction in which a compression ratio is increased, a second fluid chamber (R6) which is provided between the piston rod and the regulation member and is configured to store the working fluid, a supply flow path (R7) which is configured to guide the working fluid supplied to the second fluid chamber, a discharge flow path (R8) which is configured to guide the working fluid discharged from the second fluid chamber, and a flow rate regulation unit (15b) which is provided in the discharge flow path and is configured to regulate a flow of the working fluid when the piston rod approaches the regulation member.